﻿using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace SchoolCardSystem
{
    public partial class ValidataCode : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string checkCode = CreateRandomCode(4); 
            Session["CheckCode"] = checkCode; 
            CreateImage(checkCode); 
        }
        private string CreateRandomCode(int codeCount)
        {
            string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z";
            string[] allCharArray = allChar.Split(',');
            string randomCode = "";
            int temp = -1; Random rand = new Random();
            for (int i = 0; i < codeCount; i++)
            {
                if (temp != -1)
                {
                    rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
                }
                int t = rand.Next(35);
                if (temp == t)
                {
                    return CreateRandomCode(codeCount);
                }
                temp = t;
                randomCode += allCharArray[t];
            }
            return randomCode;
        } 
        private void CreateImage(string checkCode) 
        { 
        int iwidth = (int)(checkCode.Length * 11.5); 
        System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20); 
        Graphics g = Graphics.FromImage(image);
        Font f = new System.Drawing.Font("Fixedsys", 10, System.Drawing.FontStyle.Bold); 
        Brush b = new System.Drawing.SolidBrush(Color.DarkBlue); 
        //g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height); 
        g.Clear(Color.LightBlue); 
        g.DrawString(checkCode, f, b, 3, 3); 
        Pen blackPen = new Pen(Color.Black, 0); 
        Random rand = new Random(); 
        //画图片的前景干扰线
        for (int i = 0; i < 100; i++)
        {
            int x = rand.Next(image.Width);
                int y = rand.Next(image.Height);
                image.SetPixel(x, y, Color.FromArgb(rand.Next()));
        }
        //画图片的边框线
        g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

        System.IO.MemoryStream ms = new System.IO.MemoryStream(); 
        image.Save(ms,System.Drawing.Imaging.ImageFormat.Jpeg); 
        Response.ClearContent(); 
        Response.ContentType = "image/Jpeg"; 
        Response.BinaryWrite(ms.ToArray()); 
        g.Dispose(); 
        image.Dispose(); 
        } 
        //g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height); 
        //g.Clear(Color.Blue); 
    }
}